industrial chemistry Flashcards
contributions of chemistry to society
1- provides chemicals, pharmaceutical, fuels, medicines, agrochemicals, etc
2- provides materials such as plastics, semi-conductors, synthetic fibres, etc
3- provides stable well paid employment and contributes to knowledge economy
james muspratt
nationality: Irish
field: chemist, industrialist
“father of the modern chemical industry”
principles of industrial chemistry
batch process
continuous process
semi-continuous process
batch process
reactants/feedstock are allowed to react for a fixed time with each other inside a vessel known as a batch reactor, under controlled conditions of temp and pressure. When reaction complete, product is isolated
continuous process
feedstock continually fed in at one end of plant + product continually removed at other end. All case studies are continuous
semi-continuous process
combination of batch process + continuous process. First stage involves batch process to make product, second stage involves continuous process where product is purified using feed from various batch reactors
batch process advantages
- low capital costs
- easier to cater for slow reactions
- versatile (usable for diff processes)
- usable for trial runs
- suit seasonal products
batch process disadvantages
- time consuming + labour intensive
- contamination more likely
- difficult to control exothermic reactions
continuous process advantages
- low risk of contamination since only one product is being made
- long periods of use w/o stopping for maintenance
- suitable for large scale production
- long periods between maintenance
continuous process disadvantages
- high capital costs
- less flexibility as plant is tailor-made for a specific product
- not cost effective unless run at full capacity
characteristics of an industrial chemical process
raw materials: limestone from local quarry and seawater from Boyne estuary
feedstock: calcium hydroxide and purified seawater
reactants are called feedstock and produced from raw materials
reaction rate
-main reaction is fast
MgCl₂ + Ca(Oh)₂ –> Mg(OH)₂ + CaCl₂
- to slow process down for formation of large crystals, incoming seawater is diluted with spent seawater
- reaction mixture is seeded with Mg(OH)₂. High temp of 900°C speeds up loss of water from MgO
Mg(OH)₂ –> MgO + H₂O
products
co-products
by-products
product yield
co-products
other products made along with main product - in this case, CaCl₂
by-products
products made from side reactions, which reduce yield of main product - no by-products in this case
product yeild
2g MgO from a litre of seawater
waste disposal and effluent control
- dust removed by electrostatic precipitators
- gases scrubbed to remove SOx + grit
- used seawater contains Ca(OH)₂ which is alkaline + has to be neutralised to reduce pH
- filtered to remove suspended solids before being released back to sea
quality control
analysis of all reactants + products are carried out at every stage. Acid-base titrations used + x-ray fluorescence is an instrumentation technique used to test purity of MgO crystals
safety
- ongoing health + safety training for staff on site
- personal protective equipment (ppe) - helmets, boots, goggles, ear plugs, clothing
costs
fixed costs
variable costs
fixed costs
- those that have to paid regardless of rate of production of plant
- labour, plant depreciation, repayment of loans etc.
variable costs
- depend directly on rate of production of plant
- costs of raw materials, costs of effluent treatment and disposal, distribution costs, plant maintenance, administration, etc
how to reduce costs
recycling + using waste gases for heating
site location
- plentiful supply of seawater from Boyne estuary
- site located near local limestone quarry w/ good road + rail network for easy transport
- highly skilled workforce available
- site had suitable equipment already as it was previously a cement factory
